1. Field of the Invention
This invention relates generally to baseball bats, particularly to training bats with adjustable weight and balance for use in improving hitting accuracy, and for improving the transition from the aluminum bats used in collegiate games to wood bats used in professional games.
2. Prior Art
In the field of sport, it is generally agreed that hitting a thrown baseball is the single most difficult skill to master. Mastering this skill requires hundreds of hours of precise batting practice. Without practicing as perfectly and precisely as possible, the batter cannot acquire such hitting skill in the most efficient manner, if ever.
A conventional regulation baseball bat is comprised of a larger diameter hitting portion and a much smaller diameter handle portion. The hitting portion is larger for hitting the ball easier, and also heavier for positioning the center of gravity closer to the distal end of the bat for greater hitting power. Different models of bats handle differently because of variations in weight and balance. Such handling differences are particularly noticeable between solid wood bats and hollow aluminum bats since wood bats tend to be heavier at their distal ends. Aluminum bats are favored by amateurs because they are lighter and thus easier to swing against fast pitches, and they are much more durable. Wood bats are required by regulations for professional use.
After using a particular bat long enough, a player will become familiar with the feel of the bat and remember its handling qualities. Some highly experienced players can distinguish extremely small weight and balance differences. A player's performance will suffer if he switches from a familiar training bat to a different handling game bat for competition. Therefore, players prefer to practice with bats which are identical in handling to their game bats. Also, former amateur players who are used to aluminum bats generally have difficulty transitioning to wooden bats when they become professionals because of the vast handling differences.
Some prior art bats are provided with weight inserts for adjusting their weight. For example, a conventionally shaped bat disclosed in U.S. Pat. No. 1,499,128 to Shroyer, Jr. is provided with a weight insert which is threaded into its distal end. The weight insert may be cut to any length to adjust the total weight of the bat. Since the balance of the bat is affected by the size of the weight insert, the desired balance is unlikely to be achieved simultaneously with the desired weight. Although some adjustable bats include movable weights that can change the balance independently of the total weight, the movable weights might rattle or come loose during rigorous use. Therefore, most weighted bats are not suitable even for practice.
Another conventionally shaped bat disclosed in U.S. Pat. No. 2,379,006 to Johnson is provided with weights positioned in a hollow tube. The total weight of the bat is adjusted by changing the size or number of the weights. The balance of the bat can be adjusted by changing the position of the weight along the tube. The weight is fixed in a selected position by cork spacers at its opposite ends. Since the position of the weight is determined by the length of the spacers, the proper balance can only be achieved through a long trial-and-error process of trying different spacers and through extraordinary effort, so that the bat is not practical to use.
Most bats have a conventional shape in which the hitting portion is substantially larger in diameter than the handle portion. A training bat with a substantially smaller diameter hitting portion is disclosed in U.S. Pat. No. 4,682,773 to Pomilia. The smaller diameter hitting portion improves accuracy by requiring a more precise swing to hit a ball squarely. However, it is disclosed as much heavier than a conventional bat, and has a weight-to-length ratio which is constant along the bat rather than being greater near the end of the bat. Since its weight and balance are not adjustable and significantly different from those of a conventional bat, it is not desirable as a practice bat.